SIOUX FALLS, S.D. -- A half-hour after they got their assignment, several of Katie Gregg's second-graders still were at their desks, headphones plugged into their iPads, reading along with "The Princess and the Frog" and answering questions about the story on a worksheet.

But those who were finished were not waiting for their peers.

Sam found a spot against the wall and used his iPad to record himself reading the fairy tale aloud. Brock chose a different story from his iPad and was answering third-grade-level questions on reading comprehension. Another classmate was finding words from a set of seven letters on an iPad app called Chicktionary Coop.

Meanwhile, their teacher and groups of three students at a time were engaged in some low-tech word identification with paper flash cards.

Within two years, every K-2 classroom in the Sioux Falls School District will look like Gregg's room at R.F. Pettigrew Elementary. Each student will be assigned a $499 iPad for school use, while those in grades 3-12 get $279 Google Chromebooks, at a total initial cost of $7.3 million. It's known as a 1:1 initiative.

The school district's announcement had some residents bristling at the cost of the devices, which will be paid for by local property taxes. Expected to last four years before they are replaced, the technology will cost close to $2 million for each year they are used; the district will spend about as much on the wireless devices in the coming years as they'll spend on textbooks.

But school districts across the country increasingly see wireless computing devices as necessary furniture. Done right, 1:1 schools can reduce student behavior problems while raising test scores and graduation rates, according to Project RED, a national study of technology's impact in schools.

For Gregg, the promise of the 1:1 initiative is differentiating instruction – the elusive teaching goal of meeting the learning styles of all two dozen students at the same time.

"They can go back and read it on their own instead of me standing up here and reading it," she said. Some need to read the fairy tale multiple times, while other students can move on to other things. "That's that differentiation – kind of a big deal."

A fourth-year teacher whose master's program focused on technology integration, Gregg received one of the district's 11 grants in 2011-12 for teachers who wanted to test out iPads or other devices. By the end of the year, she said, all of her second-graders tested at grade level or better in both math and reading.

"I credit it to the small-group differentiation," she said.

Her class started out using the iPads during reading lessons, added math, and now they use them daily and "for every single content area," she said.

The apps are engaging. Students have taken a virtual field trip through the Egyptian pyramids via Google Earth, recorded short videos with iMovie and made books with Scribble Press.

"You'd think the novelty would wear off, but it doesn't," Gregg said. "It's been a dream come true. It's just crazy to see where kids take their own learning."

For some of the other teachers with technology grants, a wireless device for every student is about continuity between school, life and work.

High school chemistry teacher Katie Pabst shares 30 iPads with two other teachers. The technology has turned her classroom into a virtually paper-free environment.

The iPads haven't made a huge difference in how Pabst teaches, and she doesn't expect next year's Chromebooks will either. But she's glad the district is giving students the kind of tools they use outside of school.

"They all use their cellphones, Facebook, etc." at home, she said. "I think it just makes school more relatable."

A risk for schools that implement 1:1 initiatives is that teachers won't adapt, and the devices go unused.

"One of the big problems is integrating it into the work of teachers," said Rich Halverson, associate professor in educational leadership and policy analysis at the University of Wisconsin, who co-wrote "Rethinking Education in the Age of Technology."

"There's typically a couple years where teachers get accustomed to saying, 'I'm not the only one with information in this classroom,'" and draw on what students can find through the Internet. "That's a transition that takes a little time."

Generally, though, Halverson thinks schools' embrace of technology is long overdue. For years, schools have been banning the use of personal electronics in the classroom rather than encouraging students to use them in their studies.

"To me, that's just been backwards," he said.

Jennie Magiera, digital learning coordinator for a network of 25 Chicago Public Schools buildings, said Sioux Falls was wise to experiment with technology grants before committing to a device for every student.

But to get the most out of the iPads and Chromebooks, Magiera said, the district must commit to ongoing training throughout the year, not just at the start.

"If done well, it's fantastic, and I've seen amazing 1:1 programs," she said. "The one common denominator across the board ... is always responsive, ongoing professional learning."

In Chicago, students use iPads through fourth grade before graduating to Chromebooks.

Magiera said iPad apps work better for kids still developing their fine motor skills, and they don't have to go through the step of logging in to Google Drive. Chromebooks don't print and don't have cameras either, which makes the iPads more useful in the younger grades.

Magiera's schools also provide older kids with iPads for their math classes. A Chromebook may be great for research and writing, but it doesn't do much for calculations or illustrating math problems.

School districts across the country have made much larger iPad buys, but a Google spokeswoman said Sioux Falls' planned purchase of 17,500 Chromebooks represents "one of the largest" such purchases. Judging by other district's experiences, they should expect some bumps in the road.

Peter Sanchioni, superintendent of the public school district in Natick, Mass., said during an Education Week webinar last week that his district was deliberate in implementing a 1:1 laptop initiative. They first bought Macbooks for teachers and three years later got some for eighth-graders. This year, they added grades 9-12.

That taking it slow is "what led us to success," he said. "We were able to work out a lot of glitches (last) year."

The biggest problem they encountered was students who used a browser that circumvented the school district's content filters.

But overall, the initiative has been a success, Sanchioni said. More high schoolers are turning in their homework, and there's been a big jump in the number of eighth-grade honor roll students.

He said it's because the school now uses the same kind of tools that students have been using since birth, so they're more engaged at school.

"Because they've used these tools so extensively in their lives, they want to receive information differently," he said.